In this grant proposal, studies are presented to determine which tick (Amblyomma americanum) salivary gland antigens are responsible for the induction and elicitation of host immune resistance. Various salivary gland derived substances will be collected from live ticks and assayed for antigenicity by in vitro and in vivo techniques. The results from these studies will lead to the isolation and characterization of the resistance-associated antigens by various chromatographic and electrophoretic techniques. Such studies will elucidate the kinetics of antigen production and release. Once the crucial tick antigens are in hand, these substances will be tested for their ability to immunize hosts against ticks. Since we already have pure anti-tick antibody (7SIgG1) in hand, the use of this important reagent as a probe will facilitate our search for crucial tick antigens. In addition, we plan to utilize mice as tick hosts to generate monoclonal antibodies directed at various tick antigens. The production of these highly specific antibodies will increase our reportoire of probes able to isolate crucial antigens from crude tick extracts. With the crucial antigen(s) in hand for eventual amino acid sequencing, and eventual insertion of the corresponding genes into bacteria, it may be possible to achieve large scale antigen production for vaccine development for use in cattle. Exploitation of these newer technologies are big steps that require years of complex work, but the essential first step has been achieved, that is the isolation of specific antibody (7SIgG1) that transfers immune resistance and may be monospecific for a crucial tick antigen. The studies proposed span the disciplines of entomology, parasitology, immunology and molecular biology. Although the proposed studies are complex and sophisticated, these diverse areas of research are within our ability and new information of theoretical and practical importance should be generated.